Telephone-transmitter.



0. T. MASON.

TELEPHONE TRANSMITTER.

APPLICATION FILED JULY 5, 1910.

11,007,883, Patented Nov. 7, 1911.

WITNESSES: JNVENTOR.

ATTORNEY.

COLUMBIA PLANOQRAI?! co wAsfimmoN, B; c.-

UNITED STATES PATENT OFFICE.

CHARLES T. MASON, OF SUMTER, SOUTH CAROLINA, ASSIGNOR TO THE SUMTERTELE- PHONE MFG. OO., OF SUMTER, SOUTH CAROLINA, A CORPORATION OF SOUTHCARO- LINA.

TELEPHONE-TRANSMITTER.

Specification of Letters Patent.

Patented Nov. '7, 1911.

declare the following to be a full, clear, and

exact description of the invention, such as will enable others skilledin the art to which it appertains to make and use the same, referencebeing had to the accompanying draw- 3 ings, and to the letters andfigures of refer" ence marked thereon, which form a part of thisspecification.

My invention relates to telephone transmitters and consists of meanswhereby the sound receiving diaphragm is insulated from the circuit andpermanently located in the front of the instrument without the use ofresilient packing. I also provide a casing for inclosing the operativeparts to protect them from mechanical injury and arrange this casing sothat it is completely insulated from the circuit, yet carries all theoperative parts of the instrument including the terminals for theconnection of the circuit wires.

In the accompanying drawings Figure 1 is a vertical longitudinal sectionthrough a transmitter illustrating my invention. Fig. 2 is a rear viewof a transmitter showing the rear casing with terminals mounted thereon.Figs. 3 and 4 show arrangements for insulating the diaphragm from thecircuit.

Referrlng to Fig. 1 which shows a telephone transmitter of a well knowntype, I provide in the usual front plate 1 an annular groove 2 adaptedto receive the flanged edge 3 of the usual sound receiving dia phragm 4.The fact that the edge 3 seats itself firmly in the groove 2 serves tolocate the diaphragm centrally in the front plate. The resilient packingor rubber band heretofore used toinsulate the diaphragm from the frontis omitted as I provide other and more efficient means of insulationhereinafter described.

At 5 is shown a cell containing the variable resistance medium. Thiscell may be of any of the well known types, and constitutes the portionof the instrument through which an electric current must pass tobesubjected to the varying impulses from the sound receiving diaphragm 4.Interposed between the cell and the sound receiving diaphragm I provideposts 6 and 7 which are tipped with suitable insulating material wherethey bear against the sound receiving diaphragm, consequently, currententering at terminal 8 flows through piece and screw 9 to the spring 10to the cell forming one electrode (in this type of instrument) throughthe granular resistance medium in the cell to the other electrode andits support 11, and to terminal 12. Owing to the insulation at points13, 14, and 15, and the tips 6 and 7, the circuit is confined entirelyto the cell, its supporting members, and the terminals, the entirecasing and diaphragm being insulated.

An alternate method of insulating the diaphragm is shown in Fig. 3. Herethe pins 16 and 17 are attached to the sound receiving diaphragm and areequipped at their outer ends with insulating points 18 and 19 which bearagainst the cell 5, thereby accomplish ing the same result as theconstruction shown in Fig. 1.

Fig. 4 shows another method of insulating the diaphragm, the insulation20 being interposed between the diaphragm 4 and the cell 5, saidinsulation being independent of the cell or the diaphragm and being heldin position by the depression 21 in the diaphragm, and point 22 on thecell or front electrode, and it is obvious that any form of cell can beused, the purpose of the insulation 20 simply being to separate the cellfrom( the diaphragm.

By my improved arrangement corrosion of the diaphragm due toelectrolytic action is eliminated, because the diaphragm does not formpart of the circuit and moisture collecting between the diaphragm 4 andthe front 1-as for instance in the space 25- has no tendency tointerfere with the operation of the instrument.

The expense incident to the renewal of such perishable parts as oiledcloth, celluloid, or rubber, used heretofor all of which 1v rapidlydeteriorate when subjected to moisture, is eliminated by the flange 3firmlv seated in the depression 2 in front plate 1. And in addition thediaphragm is held centrally in relation to mouth piece 26 and istherefore always in the best position to secure the maximum results.

To center the diaphragm it has been necessary to attach the cell tosame, and, in the event of the diaphragm shifting position in 'thecasing, a strain is thrown on the cell which interferes with theoperation of the instrument.

By my improved construction groove 2 holds the diaphragm securely inplace and it cannot shift. The necessity for attach-. ing the diaphragmto the cell is also obviated, and all possibility of straining the cellis eliminated.

Attached to the front plate 1 are the posts 27 and 28 supporting therear casing 29. This eliminates the bridge usually used and carries allthe parts of the transmitter except the sound receiving diaphragm 4.

This casing is secured to the posts by screws or other suitable means30, 31, 32 and 33. A suitable flange or projection indicated at 34 isprovided between the front plate and the rear casing to permit of thetransmitter being placed in the usual back shell, which inclosesterminals 8 and 12. In placing transmitters in the back shell it hasoften occurred heretofore that the connecting wires, or cords have beenjammed against the cell or sound receiving diaphragm thereby interfering with their operation, but it will be observed that with myimprovement this is impossible, the rear casing 29 completelyinclosingand protecting all of the vital parts. Having thus described myinvention, I

claim and desire to secure by Letters Patent the following:

A telephone transmitter comprising in combination a front plate havingan annular groove therein, near its outer edge, a diaphragm having acorrugation formed therein and adapted to fit into said groove, saidcorrugation being positioned on its outer edge portion, a back platehaving a panlike shape for inclosing the working parts of thetransmitter, said back plate being arranged to rest on the back of saidfront plate, posts secured to said front plate, means for securing saidback plate to said posts, a cell disposed in said back plate andinsulated therefrom, a spring member secured to said back plate butinsulated therefrom, and having its central portion arranged to actuatesaid cell, connections for putting the spring 50 member the cell andbinding post in series, a plurality of pins secured to said member andarranged to actuate the same, said pins being in insulated contact withsaid diaphragm and actuated thereby.

In testimony whereof I hereunto afiix my signature in the presence oftwo witnesses.

CHARLES T. MASON.

Witnesses:

CARL T. MASON, E. M. HALL.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

